1. Field of the Invention
The present invention relates to a head-up display apparatus for an automotive vehicle, and more specifically to an apparatus for displaying various vehicle related information on a half mirror disposed on the vehicle dashboard, so that the driver can see displayed vehicle information, while seeing external views through the windshield.
2. Description of the Prior Art
Recently, a display apparatus called head-up display has been used for an automotive vehicle, in which a display unit is disposed on the dashboard so that the driver can see vehicle information while seeing the outside view through the windshield during vehicle running. The display unit is a half mirror or a hologram plate.
In this apparatus, on the other hand, a liquid crystal display, a CRT (cathode ray tube), etc. are used as the projector unit to project two-dimensional images such as road maps, TV programs, etc. in addition to various vehicle information. However, since it is not desirable to allow the driver to see TV programs during vehicle running, the TV images can be displayed only when the vehicle stop is detected. Therefore, there exists a problem in that passsengers taking rear seats cannot watch TV programs while the vehicle is running. In this connection, it may be possible to provide another CRT for only TV broadcastings within the passenger compartment. In this case, however, there exists another problem in that the passenger compartment is narrowed by two CRTs.
In addition, in the head-up display apparatus as described above, since the display unit is so arranged as to be recognized only by the driver taking a front seat, there exists another problem in that passengers taking rear seats cannot see road maps or TV programs irrespective of vehicle running or vehicle halt.